Conventional peroxycarboxylic acid compositions typically include short chain peroxycarboxylic acids or mixtures of short chain peroxycarboxylic acids and medium chain peroxycarboxylic acids (see, e.g., U.S. Pat. Nos. 5,200,189, 5,314,687, 5,409,713, 5,437,868, 5,489,434, 6,674,538, 6,010,729, 6,111,963, and 6,514,556). Conventional peroxycarboxylic compositions including components such as hydrogen peroxide or mineral acid can be corrosive and, at use dilutions, may not have a sufficiently long shelf life. In addition, some conventional peroxycarboxylic acid compositions could benefit from increased sporicidal activity.
At neutral and basic pH, corrosion of soft and hard metal surfaces can be inhibited by mixtures of salts of aliphatic carboxylic acids and triazole compounds. Such mixtures are used, for example, in engine antifreeze compositions (see, e.g., U.S. Pat. No. 4,647,392). At basic pH, it is believed that the positively charged ion in the salt of the carboxylic acid is attracted to the electronegative surface of the target metal. The aliphatic portion of the carboxylic acid is believed to keep water away from the metal and thus provide a protective coating against corrosion. Such a mechanism cannot explain corrosion protection at acid pH and these compositions have not previously been shown effective at low pH.
Ongoing research efforts have strived for improved peroxycarboxylic acid compositions. In particular, these efforts have strived for compositions that have increased activity as a sporicide, that have a prolonged shelf life at use dilutions, and/or have reduced corrosiveness.